Catalytic routes and oxidation mechanisms in photoreforming of polyols

Journal Article · Thu Dec 01 00:00:00 EST 2016 · Journal of Catalysis

DOI:https://doi.org/10.1016/j.jcat.2016.08.009· OSTI ID:1344058

Sanwald, Kai E.; Berto, Tobias F.; Eisenreich, Wolfgang; Gutiérrez, Oliver Y.; Lercher, Johannes A.

Photocatalytic reforming of biomass-derived oxygenates leads to H₂ generation and evolution of CO₂ via parallel formation of organic intermediates through anodic oxidations on a Rh/TiO₂ photocatalyst. The reaction pathways and kinetics in the photoreforming of C₃–C₆ polyols were explored. Polyols are converted via direct and indirect hole transfer pathways resulting in (i) oxidative rupture of C–C bonds, (ii) oxidation to a-oxygen functionalized aldoses and ketoses (carbonyl group formation) and (iii) light-driven dehydration. Direct hole transfer to chemisorbed oxygenates on terminal Ti(IV)-OH groups, generating alkoxy-radicals that undergo ß-C–C-cleavage, is proposed for the oxidative C–C rupture. Carbonyl group formation and dehydration are attributed to indirect hole transfer at surface lattice oxygen sites [Ti_ _ _O_ _ _Ti] followed by the generation of carbon-centered radicals. Polyol chain length impacts the contribution of the oxidation mechanisms favoring the C–C bond cleavage (internal preferred over terminal) as the dominant pathway with higher polyol carbon number.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1344058
• Report Number(s): PNNL-SA-123533; KC0302010
• Journal Information: Journal of Catalysis, Vol. 344, Issue C; ISSN 0021-9517
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
photocatalysis
TiO3
H2 production
photoreforming
glycerol
polyols
oxidation mechanism